Propeller for aircraft.



J. H. SMYTH'.

PRUPELLER FOR AIRCRAFT. APPLICATION FILED JULY 21. 1916.

1,243,850 Patented Oct. 23, 1917.

'Tnn sTATas PATENT Trina.

JOHN H. SMYTH, OF ERIDGEBURG, ONTARIO, CANADA.

PROPELLER FOR AIRCRAFT.

Application filed July 27, 1916.

To all whom it may concern:

Be it known that I, JOHN H. SMYTH, of the village of Bridgeburg, in the county of Welland and Province of Ontario, Dominion of Canada, have invented certain new and useful Improvements in Propellers for Aircraft; and I hereby declare that the following is a full, clear, and exact description of the same.

A propeller for air craft, as now constructed, is provided with a set of single blades, arranged at an angle incident to a plane perpendicular to the axis of revolution, for producing when revolved, motion or pressure in the direction of such axis, the angle'of incidence governing the driving factor of the propeller; that is to say, the greater the angle of incidence up to a critical point, the greater the driving force, and vice versa. The driving force in the case of a set of single blades, however, is out of all proportion to the rotational speed, in comparison to the power which would be derived if a set of double blades were employed and the components set at difierent angles of incidence such as to produce the maximum leverage upon the blades without creating a region of rarefaction.

The object of this invention, therefore, is to obtain an increase of driving power at the usual rotational speed, and this object is attained by providing the propeller with a set of double blades arranged at such angles of incidence as to produce a greater leverage, and consequently more power at the same rotational speed, or the same power at a lower rotational speed, than in the case of a propeller having a set of single blades, the components of the double blades being arranged so that one, which may be termed the leading blade, cleaves the air at an angle of incidence such as to produce the maximum of leverage upon the blade and utilize the entire volume of air encountered, without setting up a region of rarefaction, and the other, which may be termed the following blade, set at a different angle of incidence, such as to act upon the current of air generated by the leading blade, produces the maximum leverage and utilizes the entire volume of air encountered, without setting up a region of rarefaction.

In the drawings Figure 1, is a perspective view of the Specification of Letters Patent.

Patented Oct. 23, 191%.

Serial No. 111,651.

propeller showing the arrangement of the blades;

Fig. 2, is a ing blades;

Fig. 3, is a perspective view of one of the following blades;

Fig. 4, is a detail view of the hub shown in Fig. 1; b

Fig. 5, is a perspective view of a modification of the hub shown in the preceding views;

Fig. 6, is-a cross sectional view showing the angles of incidence of the leading and following blades.

Like characters of reference refer to like detail view ofone of the lead-' parts throughout the specification and drawings. The essential feature of the invention is not so much the shape of the blades, as almost any type can be used, but it is the principle of arranging the blades in pairs, with the components of each pair at different angles of incidence to the plane of revolution, and one component in advance of the other in the circle of rotation.

In carrying out this principle, I have shown in the drawings, and hereinafter described, a convenient type of propeller, consisting of sets of double blades, a, b, anda, b, respectively, the blades 11, a being hereinafter termed the leading blades, and the blades 6, b, the following blades, the leading blades being at relatively small angles of incidence and the following blades at relatively greater angles of incidence, to the plane of the revolution of the propeller.

These blades may be integrally formed from a unitary casting or forging, or cut from a block of metal or wood, as is most suitable for the purposes for which the propeller is intended, but a convenient method of constructing the propeller is to provide a hub 0, such as is shown in Figs. 1 and 4 of the drawings, or a hub d similar to that shown in Fig. 5, or any modification of these constructions within the scope of the appended claims, and to bolt or otherwise fasten the leading and following blades, to it at appropriate angles of incidence to the plane of revolution with the leading blade in advance of the following blade in the circle of rotation. p

In Figs. 1, 4c and 5, the hub is shown to be substantially rectangular in cross section,

with two diametral extensions or hub members c disposed lengthwise of the blades. This hub construction provides shoulders 0 to engage with corresponding shoulders e, in the inner faces of the arms 6' of the blades, the inner face of each arm 6 abutting against the adjacent side of its respective hub member 0 and being formed with an elongation e overlapping its respective part of the hub and abutting against the end of the elongation of the arm of the other blade on the same side of the hub.

As shown in Fig. 1, a leading blade and 'a following blade are located on each side of the hub, for instance, the leading blade at and the following blade I) are located on one side of the hub, and the leading blade a and the following blade I) are located on the other side, with the leading blades in advance of the following blades in the circle of; rotation, and the inner faces of the arms of each of the blades engaging the corre sponding faces of the hub member a and the shoulders e of the arms 6 engaging the shoulders 0*.

Appropriate means are employed to secure the blades to the hub, such means preferably consisting of passing through the leading blade a, hub, and following blade 6, a bolt or set of bolts f, and passing through the leading blade a, hub, and following blade I), a similar bolt or set of bolts 7, these bolts rigidly fastening the leading and following blades to the hub.

As shown in Fig. 1, the hub is provided with plates 9 located at opposite sides of the hub to engage the arms of the leading and following blades, these plates being securely bolted or screwed to the hub, for the purpose of preventing the lateral displacement of the assembled parts, and as shown in Fig. 5, the top and bottom of the hub are formed with overhanging flanges h, the flanges engaging the adjacent surfaces of the arms for the same purpose as the plates 9, and as shown in Fig. 3, the leading blades are formed with shoulders a to engage the ends of the hub members 0 when the parts are assembled.

This arrangement provides for a rigid assembly of the parts and a substantial bearing for the arms of the blades upon the hub, so that when the arms and the hub are bolted together, the blades will be immovably held in their fixed relation, to resist the rotational torsion.

As shown in Fig. 1, the leading blades a, a, which are arranged in advance of, the following blades 6, b, respectively, in the circle of rotation are at a relatively small angle of incidence to the plane of the rotation of thepropeller, and spaced sufliciently from the following blades to permit of the air disturbed by the following blades clearing the propeller.

The following blades 6, b, as shown in Figs. 1 and 6, are at a relatively great angle of incidence to the plane of the rotation of the propeller, and overhang the front and rear faces of the leading blades a, a.

That part b of each following blade, overhanging the front face a of each leading blade, displaces an amount of air in proportion to the amount of leadv it may have.

That part b of each following blade, overhanging the rear face of each leading blade, acts upon the'air displaced by the front overhang b and the leading blade in proportion to the area of the overhang.

During the rotation of the propeller, the leading blades, cleaving the air, effect a displacement and set up an air current or motion in the direction of the rear overhang b of the following blades, their angles of incidence being such that a maximum leverage is obtained under the conditions previously stated.

The front overhang b of each following blade, cleaving the air, efiects a displacement toward the rear. The air so displaced by the front overhang 5 passes across the face of the following blade to the rear edge, the separation between the leading and following blades being provided for that purpose. Consequently the following blades, by cleaving the air, and by utilizing the air thus displaced, and because of their greater angle of incidence, produce a maximum of leverage.

By this construction, the driving power is greater than that of a single blade atothe same rotational speed; consequently, it is possible by the use of a propeller having a set of double blades, to derive a greater driving power at the same rotational speed, or the same driving power at a lower rota tional speed, than in the case of a propeller with a set of single blades.

Having thus fully described the nature of my invention, what I claim as'new and desire to secure by Letters Patent, is

1. A propeller comprising a double propeller blade, consisting of two components at difi'erent angles of incidence to the plane of revolution, with one component overhanging the other and separated therefrom, whereby the air displaced by the components may pass through the separation.

2. A propeller comprising propeller blades arranged in pairs with the components of each pair at difierent angles of incidence to the plane of revolution, and one component in advance of the other in the circle of rotation, the following component overhanging the leading component and separated therefrom, whereby the air displaced by the components may pass through the separation.

3. A propeller comprising propeller blades arranged in pairs with the components of eachpair at diiferent angles of incidence to the plane of'revolution, and one component in advance of the other in the circle of rotation, the following component overhanging the front and rear faces of the leading component and separated therefrom, whereby the air displaced by the components may pass through the separation.

A propeller comprising a propeller blade, consisting of two components, one of which is placed in advance of the other in the circle of rotation, the two components being at different angles of incidence and one of the components overhanging the front and rear faces of the other there being a separation between them whereby the air displaced by the components may pass through the separation.

5. A propeller comprising. a set of double propeller blades, each double blade consisting of two components, one of which is in advance of the other in the circle of rotation, and at a difierent angle of incidence thereto, one of the components overhanglng the front and rear faces of the other, there being a separation between-them whereby the air displaced by them during their rotation can pass therethrough.

Buffalo, July 10th, 1916. i

y JOHN H. SMYTH. Signed in the presence of I M. HOUSE, B. G. HYDE. 

